Don't emit canceled() until the operator is canceled
Don't emit canceled() until the operator is canceled

OpenChemistry/tomviz,mathturtle/tomviz,mathturtle/tomviz,OpenChemistry/tomviz,cryos/tomviz,cryos/tomviz,mathturtle/tomviz,OpenChemistry/tomviz,cryos/tomviz,OpenChemistry/tomviz